1. Field of the Invention
This invention relates to improvements in stuffing boxes and more particularly, but not by way of limitation, to a self-aligning, self-lubricating packless stuffing box for polish rods of producing oil and/or gas well bores, rotatable pump rods, or the like.
2. Description of the Prior Art
Many producing oil and/or gas well bores are provided with down-hole pumping apparatus operable for elevating the well fluids to the surface of the ground. The usual down-hole pumping apparatus is actuated by a surface mounted pump jack assembly which is connected with the down-hole pump by a polish rod or sucker rod string which extends longitudinally through the well bore into connection with the pump means. The reciprocation of the sucker rod string or polish rod by the pump jack actuates the downhole pump for elevating the well fluids through the well tubing for delivery through the usual pumping "T" for recovery of the fluids. It is common practice to install a stuffing box around the outer periphery of the polish rod above the pumping "T" for precluding the loss of the well fluids around the outer periphery of the polish rod. The stuffing box is normally provided with a plurality of packing members engagable with the outer periphery of the rod and the inner periphery of the housing to achieve the sealing of the polish rod. As the polish rod reciprocates with respect to the stuffing box, considerable friction may develop between the packing members and the rod, causing wear and damage to the packing member, thus reducing the sealing efficiency thereon. It is common practice to provide packing followers in the stuffing box for adjusting the pressure of the packing members against the rod to compensate for the wear of the packings. In addition, it is desirable to provide an efficient lubrication between the polish rod and the packings for reducing the wear of the packing during the operation of the rod.
The Reeves Pat. No. 3,468,374, issued Sept. 23, 1969, and entitled "Self-Cooled Oil Well Polish Rod Stuffing Box" has been devised to reduce or overcome the problem caused by frictional heat or inadequate lubrication of the stuffing box. The Reeves stuffing box includes a cooling chamber surrounding the polish rod and interposed between the upper and lower packing glands for assuring an adequate supply of lubricating fluid for the rod during reciprocation thereof. The Reeves device includes a fluid supply line and a fluid return line disposed exteriorly of the stuffing box, and in some installations their lines are subject to damage, and damage or breaking of the lines may seriously affect the efficiency of the Reeves stuffing box. The aforementioned co-pending application discloses internal passageway means for circulating or controlling the supply of fluid for the cooling chamber in order to overcome this disadvantage.
Another problem which may be encountered in connection with the polish rod is a misalignment between the pump jack and the pumping "T". This misalignment may cause undue wear on the packing members, and may squeeze the lubricant from the packing members when the pump jack is inoperative and the polish rod is suspended therefrom. The packing members may then be unduly damaged upon "start up" of the pump jack. In order to overcome this disadvantage, a swivel connection between the stuffing box and the pumping "T" has been designed as shown in co-pending application Ser. No. 483,101, filed Apr. 8, 1983 and now abandoned, and entitled "Self-Aligned Polish Rod Stuffing Box" and of which I am a co-inventor.